Prefab Accessory Dwelling Units in California
We install faster and smarter prefab accessory dwelling units in California that homeowners trust. You will get high-quality prefab ADUs, designed off-site, installed efficiently, and built to last.
4.9/5 rating from 56+ online reviews.
A Better Way to Build Your ADU
Prefab ADUs are changing how homeowners add space. Instead of long, unpredictable construction timelines, a prefabricated ADU is built in a controlled environment and then installed on your property, saving time without cutting corners.
Whether you’re exploring a modular ADU, comparing ADU kits, or looking for affordable prefabs, the goal is the same: a clean, efficient build with fewer delays.
From rental units to private living spaces, pre-built and pre-made ADU homes give you flexibility. At Sidex, we guide you through every option so you don’t just pick what’s available, you choose what actually works for your property and your goals.
Complete Prefab ADU Solutions
Custom Prefab ADU Planning
Not all prefab ADUs are one-size-fits-all. We help you choose the right size, and features, whether you’re looking for a compact unit or a spacious ADU modular home in California that feels like a full home.
Prefabricated ADU Installation
We handle the full installation of your pre-built ADU, including site preparation, foundation work, and utility connections. Our team ensures your prefabricated ADU is installed safely and correctly.
Modular & Manufactured ADU Options
From modular ADU builds to manufactured ADU units, we offer a range of solutions tailored to different budgets. If you’re searching for the best prefab ADU, we’ll help you find the right balance between cost, quality, and design.
Built with Precision, Designed for Real Living
Explore our projects to see how we build functional, durable, and visually seamless structures across Northern California.
How We Build Your Detached ADU
Consultation & Feasibility
We evaluate your property, zoning, and goals to determine what type of detached ADU makes the most sense for your space and budget.
Step 1
Design & Planning
Our team creates a custom design, including layout, materials, and utility planning. We also handle permit documentation and approvals.
Step 2
Construction
From foundation to final finishes, we manage the entire detached ADU construction process with a focus on quality, timelines, and clean execution.
Step 3
Final Walkthrough
We complete final inspections, ensure everything is code-compliant, and walk you through your new space so it’s ready for immediate use.
Step 4
Detached ADU Builders Across Northern California
We design and build detached ADUs for homeowners across key regions, serving over 57 locations.
The Bay Area
From San Francisco to San Jose and surrounding cities, we help homeowners create smart, space-efficient ADUs that increase property value and usability.
South Lake Tahoe
In mountain regions, we build detached ADU construction projects designed for weather durability, insulation, and year-round comfort.
Sacramento Region
Serving Sacramento, Roseville, and nearby areas, we deliver practical and cost-effective detached ADUs tailored to growing families and rental opportunities.
Detached ADU FAQs
What is a detached ADU?
A detached ADU is a separate residential unit built on the same property as your main home, fully independent with its own living facilities.
How is a detached ADU different from an attached ADU?
A detached dwelling stands alone, offering more privacy and flexibility compared to attached units that share a wall with the main home.
How long does detached ADU construction take?
Timelines vary, but most projects take a few months depending on design complexity, permits, and site conditions.
Can I rent out my detached ADU?
Yes. Many homeowners use detached ADUs as rental units for additional income, subject to local regulations.
Do I need permits for a detached ADU?
Yes. Every detached additional dwelling unit must meet local zoning and building requirements. We help manage this entire process.
Trustindex verifies that the original source of the review is Google.
Elizabeth Neilsen2024-07-15We needed some deck repairs and had Sidex out to give us a bid and suggestions. Best choice ever. They spent time to evaluate necessary repairs and gave us estimates. Contracted for the work. Workers were great. Very efficient and tidy. So happy with the results. Thank you Sidex. ❤️Trustindex verifies that the original source of the review is Google.Sruthi gn2024-06-15Thank you Sidex for an excellent work. They built our 12x12 deck in one day. Such a great team. We enjoyed the work .Trustindex verifies that the original source of the review is Google.Joshua K2024-06-02I recently had my dock replaced by Sidex Siding and Decking, and we couldn't be happier with how it turned out! I reached out to Andrey, and he and his team did an amazing job from start to finish. They listened to our vision for the dock, sourced high-quality materials, and maintained excellent communication throughout the process. The entire project was completed within a week, and the workmanship is outstanding. We are thrilled with how it turned out and would highly recommend Sidex Siding and Decking to anyone. Thank you, Andrey and team, for your exceptional work!Trustindex verifies that the original source of the review is Google.Rand Martin2024-05-16Excellent and meticulous work.Trustindex verifies that the original source of the review is Google.Barry Cohen2024-05-14Andrey and his team repaired a fence for me recently and I could not be happier with the work. I know he went out of his way to keep on schedule to do that work on the day upon which we agreed even though it was inconvenient for him. The team arrived on time, did the work efficiently and I believe for a reasonable price. The end product, the repair, was excellent. I would use this company again.Trustindex verifies that the original source of the review is Google.Nicole2024-05-13I am ???? grateful for this wheelchair ramp. They worked so hard to get it done in one day, so I could take my brother to the doctor by myself without using medical transportation. This is the first company that heard my needs and made it happen. I recommend Andrey! They are gentle, kind, and professional. Outstanding!Trustindex verifies that the original source of the review is Google.Elisey Borisov2024-05-09Thank you Sidex. Great team, easy to work with. Customer service was outstanding, answered all of my questions quickly, made me feel comfortable throughout all stages of the process. Great job guys, with new windows and siding my house looks brand new!Trustindex verifies that the original source of the review is Google.Any Way Moving2024-05-09I recently had the pleasure of hiring Sidex for siding installation on my home, and I couldn't be more impressed with the results. From start to finish, the entire process was seamless and professional. Firstly, the team at Sidex demonstrated excellent communication skills, promptly addressing all my inquiries and concerns. They provided a detailed quote outlining the scope of work and timeline for completion, which was very helpful in setting expectations. When it came to the installation itself, the craftsmanship exhibited by the crew was outstanding. They worked diligently, paying close attention to detail to ensure a flawless finish. The siding not only looks beautiful but also feels sturdy and durable, providing added protection to my home. Moreover, the project was completed within the agreed-upon timeframe, without any delays or unexpected issues. The crew was respectful of my property, keeping the work area clean and tidy throughout the process. Overall, I am beyond satisfied with the quality of work delivered by Sidex. Their expertise, professionalism, and attention to detail have truly transformed the exterior of my home. I would highly recommend their services to anyone in need of siding installation or any other home improvement projects.Trustindex verifies that the original source of the review is Google.Ariel Hernandez2024-05-09Absolutely killed it! From our first interaction, and up to the final moments of the project they showed true professionalism and good quality work with a smile on their face! I couldn’t recommend a better company, thank you!Trustindex verifies that the original source of the review is Google.Angel Solis2024-05-09Trusted company. Whatever your needs maybe be, regarding siding and decking, be sure that you can you trust Sidex.
